lib/egl: fix type cast and warnings

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
lib/egl: add EGLConfigAttribs::caveat and related services

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
lib/egl: add EGLConfigAttribs::conformant and related services

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
lib/egl: add EGLConfigAttribs.buffer|blue|green|red|depth|stencil_size

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
Merge: Config related services in EGL

Allows to know what you get in the available display configurations.

Pull-Request: #382
Reviewed-by: Jean Privat <jean@pryen.org>